Catheter with multilayer tube

ABSTRACT

An interventional catheter for angioplasty and the like, comprising a catheter tube formed of two superposed layers of materials different from one another. The inner layer is comprised of a low friction nonkinkable material to avoid risk of clogging of a guide wire in the longitudinal lumen. The outer layer is comprised of a material with higher friction coefficient than the material forming the inner layer. The balloon is welded at its distal end to the outer layer of the catheter tube. The proximal end of the balloon is welded to a tube surrounding the catheter tube.

This application is a continuation of U.S. patent application Ser. No.09/317,293, filed May 24, 1999, now U.S. Pat. No. 6,471,673; which is acontinuation of U.S. patent application Ser. No. 08/936,352, filed Sep.24, 1997, now U.S. Pat. No. 5,961,765; which is a divisional of U.S.patent application Ser. No. 08/657,004, filed May 28, 1996, nowabandoned; which is a continuation of U.S. patent application Ser. No.08/309,234, filed Sep. 20, 1994, now abandoned; which claims priority toEuropean Patent Application No. 93117403.1, filed Oct. 27, 1993.

BACKGROUND OF THE INVENTION

This invention relates to an interventional catheter comprising acatheter tube having two superposed layers of materials secured inrelation to one another and with mechanical properties differing fromone another, a longitudinal lumen in said catheter tube for the slidingfit of a guide wire, and a balloon with a proximal end and a distal end,whereby the distal end sealingly surrounds said catheter tube, wherebythe catheter tube has an inner layer forming the longitudinal lumen andan outer layer forming the outer surface of the catheter tube.

Over the wire catheters are now widely used for interventions such aspercutaneous transluminal angioplasty. A problem with these catheters isthat the guide wire may clog into the longitudinal lumen of thecatheter; as a result, the guide wire may follow the balloon uponwithdrawal thereof after the inflation procedure, thereby making itnecessary to re-insert the guide wire into the threaded area of theblood vessel for re-positioning a balloon therein in case a secondinflation is needed. Apart of this, the catheter has to achieve anacceptable compromise between the requirements of some stiffness toassure good pushability and of some flexibility to assure kinkresistance. In addition, the catheter has to permit safe attachment ofthe balloon to the catheter tube.

The document WO 92/11893 describes an intra-aortic balloon apparatuscomprising a hollow catheter in which is located an elongated memberforming a central lumen extending out of the catheter at the distal endthereof. An aortic pumping balloon is positioned over the elongatedmember; the distal end of the balloon is bonded to a tip affixed to thedistal end of the elongated member, and its proximal end is bonded tothe distal end of the catheter. In order to achieve a balance offlexibility and remains and to avoid kinking, the elongated member isformed of an inner layer comprised of a soft elastomeric material toimpart flexibility to the tubing, and the outer layer is comprised of ahard plastic material to impart structural support to the elongatedmember. The combination of these two layers is made to achieve a verydurable and flexible structure exhibiting a low kink radius. Thisballoon apparatus cannot be loaded with a guidewire and moved intotortuous vessels with the guidewire loaded inside the elongated tube.The friction between guidewire and the elongated member increasesdistinctively when the elongated member is shaped into curves. The aboveprocedure would therefore risk that the spiral wound guidewire could becaptured in the soft elastomeric plastic material of the inner layer ofthe elongated member. Although the outer layer of the elongated memberthat is coextruded onto the inner layer is formed from nylon, a materialwhich is directly weldable to a wide variety of materials, this balloonapparatus cannot be introduced into narrow vessels or narrow stenosesnor can it be passed through narrow punctures to enter the bloodvessels. This is because of the relatively large profile of the foldedballoon. The large profile is due to the distal fixture of the balloonto the elongated member. The balloon is bonded to an intermediate tipelement which in turn is bonded to the elongated member.

U.S. Pat. No. 4,323,071 describes a combination guiding catheterassembly and dilating catheter assembly. The guiding catheter assemblycomprises a first flexible tubular member formed of a material with lowcoefficient of friction and high flexibility; as this first tubularmember is too flexible to serve as a guiding catheter because it couldnot be properly manipulated in the body of a patient, a second tubularmember made of a heat shrinkable tubing is provided to encase the firsttubular member. The distal end of this assembly is preshaped to form ashape corresponding to the standard coronary catheter and the proximalend of the assembly is provided with attachment means to provide aleak-proof adhesive-free connection. The dilating catheter assembly isdisposed within the guiding catheter assembly and comprises a firsttubular member coaxially disposed within a second tubular member havingformed thereon a balloon at its distal end, both these tubular membersbeing made of shrink tubing; an annular flow passage between the firstand second tubular members allows introduction of fluid into the balloonfor inflation thereof. The proximal end of this assembly is inserted inan adapter body for connection to an appropriate syringe system. Adilator consisting of a flexible plastic tube with a teflon coated guidewire therein is used to position the guiding catheter assembly in theproper location. Within this frame, the guide wire is first insertedconventionally into the blood vessel; the dilator is then positioned inthe guiding catheter assembly to straighten it, and the dilator andguiding catheter are passed over the guide wire into the blood vessel;when the guiding catheter is in the proper location, the dilator andguide wire are withdrawn from the guiding catheter and the dilatingcatheter assembly can be inserted into the guiding catheter assembly,which operation is facilitated be the low coefficient of friction of thefirst tubular member of the guiding catheter assembly. A small guidewire may be utilized if necessary to precisely position the balloon ofthe dilating catheter assembly; if so, this small guide wire has to beinserted into the first tubular member of the dilating catheter assemblyso that it extends from the distal portion thereof. This guide wire maybe removed once the balloon is in the proper location.

This publication shows a catheter shaft made from a composited materialthat is achieved by heat shrinking. The material for the inner layer ofthe composite material is selected from materials rendering lowfriction. Any instrument inserted into a catheter shaft made from thiscomposite material can easily be moved inside the shaft even after theshaft has been bent and is kept in narrow curves. The shaft for thedilation balloon catheter shown in this publication does not usecomposite material for its construction. It uses conventional materialin one single layer. Because the balloon must be welded or otherwisesecurely bonded to the catheter shaft to withstand the extraordinaryhigh inflation pressures used in angioplasty, the shaft material forthis dilatation balloon catheter has to be selected for good bondcharacteristics and cannot be selected for good frictioncharacteristics. Therefore this catheter still presents the problem thatin tortuous vessels, when the catheter shaft has to follow numerousbends of the vessel, the guidewire can be captured in the shaft. This isspecifically troublesome since the dilation catheter has to advance muchdeeper into the branched vessel system than the guiding catheter whichin this publication is shown as made from composite material. For adilatation catheter the length of the friction creating shaft is longerthan the shaft of the guiding catheter and additionally the dilatationcatheter shaft is exposed to more vessel curves.

SUMMARY OF THE INVENTION

The purpose of the present invention is to present an interventional lowprofile balloon catheter that can be moved into tortuous vessels with aguidewire inside the catheter without the risk of the guidewire beingcaptured or clogging in the catheter.

To this effect, the interventional catheter according to the inventioncomplies with the definitions given in the claims.

In that way, there is no more risk of having the guide wire clogging inthe longitudinal lumen of the catheter tube, in particular uponwithdrawal of the balloon. Withdrawal and re-positioning of a balloonfor repeated inflation is therefore rapid, safe and precise, becauseduring withdrawal of the balloon the guidewire can be left in place withthe tip of the guidewire at the site of the treatment in the vesselsystem. As the inner layer forming the longitudinal lumen is separatedfrom the balloon by the outer layer, the choice may be made towardsmaterials having the most appropriate friction and kink resistancecoefficients, while safe attachment of the balloon may be made at willon an outer layer of the catheter tube which may be chosen without beinginfluenced by the properties of the inner layer.

The inner layer and the outer layer may be congruent in length so thatthe catheter shaft can be produced in long tubes which are cut intolength to form the individual catheter tube.

Where the two layers of the catheter are produced by extruding the outerlayer over the inner layer, a specifically reliable catheter tube isformed in a continuous process. To heat shrink the outer layer onto theinner layer would not allow a continuous process because of the presenceof an inner core inside the inner layer. This core has to take up theradial pressure during the heat shrinking process and has to be removedafter heat shrinking.

The seal between the balloon and the catheter tube may be achieved bywelding the balloon material to the outer layer of the catheter tube.This allows the design of balloon catheters that withstand theextraordinary high inflation pressures used in angioplasty so that thesecatheters also show the low clogging risk and the low profile given bythe invention.

In a preferred form of the invention, the inner layer forming thelongitudinal lumen of the catheter tube is made of a polyethylene or ofa high density polyethylene, both of which assure an extremely lowfriction coefficient and an appropriate kink resistance coefficient. Inanother preferred embodiment, the catheter tube will comprise an outerlayer made of a polyamid assuring easy welding of the balloon and a goodstiffness at that level. These and other objects will become readilyapparent from the following detailed description with reference to theaccompanying drawings which show, diagrammatically and by way of exampleonly, a preferred embodiment of the invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cut out of this embodiment.

FIG. 2 is a section according to line I—I of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The interventional catheter shown in FIGS. 1 and 2 comprises a cathetertube 1 which is formed, in this embodiment, of two superposed continuouslayers 2 and 3 extending all over the length of the tube 1; this tubing,which may be achieved by the known co-extrusion technology, i.e. byextruding the outer layer over the inner layer, is comprised of apolyethylene, preferably a high density polyethylene, for the innerlayer 2, and of a polyamid for the outer layer 3. The inner layer 2 thusforms a longitudinal lumen 12 with a very low friction coefficient,lower than that of the material forming the outer layer 3, and a nonkinking capacity, while the outer layer 3 is easily weldable to thematerials commonly used for making balloons for angioplasty and thelike.

Over the distal portion of the catheter tube 1 is positioned a balloon 4the distal end 5 of which is sealed to the outer layer 3 of the cathetertube 1, for instance by welding.

A tube 7 is arranged over the catheter tube 1, at a radial distancethereof, thus defining an inflating lumen 8 for the balloon 4. Theproximal end 6 of the balloon 4 is welded onto the distal end of saidtube 7.

The tube 7 is exemplified here as being made of two tubes 9 and 10longitudinally affixed to one another. Preferably the tube 9 and 10shall be made of a polyamid to achieve easy fixing by welding proceduresand to obtain a stepped stiffness. The proximal end of tube 10 isconnected to conventional fittings (not shown) to feed the balloon anddrive the catheter assembly. Inside the catheter tube 1 is placed aguide wire 11 in sliding fit within the inner layer 2 forming thelongitudinal lumen 12.

As a variant, the two tubes configuration of the tube 7 may be replacedby a single tube or by a configuration having more than twolongitudinally affixed tubes.

1. A catheter comprising: an outer elongate tubular member having aproximal end and a distal end, wherein the outer elongate member has afirst stiffness at a first location and a second stiffness less than thefirst stiffness at a second location, the second location being distalof the first location; an inner elongate tubular member having aproximal end and a distal end, the inner elongate tubular member havingan inner surface defining a first lumen and having an outer surface,wherein at least part of the inner surface has a first coefficient offriction, and at least part of the outer surface has a secondcoefficient of friction that is greater than the first coefficient offriction; and a balloon; wherein the inner elongate tubular member isdisposed coaxially within at least a portion of the outer elongatetubular member to define a second lumen therebetween, and wherein theballoon is attached to the distal end of the outer elongate tubularmember and the distal end of the inner elongate tubular member.
 2. Thecatheter of claim 1, wherein the outer elongate tubular member includesseveral sub-elongated members joined together to effect the reduction instiffness.
 3. The catheter of claim 1, wherein the inner elongatetubular member is adapted to prevent kinking, and the outer elongatetubular member is adapted to provide stiffness for the catheter.
 4. Thecatheter of claim 1, wherein the inner elongate tubular member compriseshigh density polyethylene.
 5. The catheter of claim 1, wherein the innerelongate tubular member comprises polyamide.
 6. The catheter of claim 1,wherein the inner elongate tubular member comprises high densitypolyethylene and polyamide.
 7. The catheter of claim 1, wherein theinner elongate tubular member consists essentially of high densitypolyethylene and polyamide.
 8. The catheter of claim 1, wherein theinner surface of the inner elongate tubular member comprises a firstmaterial and the outer surface of the inner elongate member comprises asecond material.